P2P architecture for self-atomic memory

We propose an architecture for self-adjusting and self-healing atomic memory in highly dynamic systems exploiting peer-to-peer (P2P) techniques. Our approach, named SAM, brings together new and old research areas such as P2P overlays, dynamic quorums and replica control. In SAM, nodes form a connected overlay. To emulate the behavior of an atomic memory we use intersected sets of nodes, namely quorums, where each node hosts a replica of an object. In our approach, a quorum set is obtained by performing a deterministic traversal of the overlay. The SAM overlay features self-capabilities: that is, the overlay self-heals on the fly when nodes hosting replicas leave the system and the number of active replicas in the overlay dynamically self-adjusts with respect to the object load. In particular, SAM pushes requests from loaded replicas to less solicited replicas. If such replicas do not exist, the replicas overlay self-adjusts to absorb the extra load without breaking the atomicity. We propose a distributed implementation of SAM where nodes exploit only a restricted local view of the system, for the sake of scalability.